Art of cracking and coking



June 16,V 1936. H. L. PELZER ART oF cRAcKING AND coxme HYDROCARBON 0111s Original Filed April 17, 1929 s ATTORNEYS INVENTORl #arr/f L, Pe /zer Bgm;

Reissued Jane 16,1936 s' Refzooll UNITED STATES PATENT oFI-lcE Aar oF cRAcxING AND como' HYDROCARBON oiLs Harry L. Pelzer, Houston, Tex., assignor to Sinclair Refining Company, New York, N. Y., a I

corporation of Maine original No. 1,937,163, dated November 2s, 1933,

serial Nu. 355,780, `April 17, 1923. Application for reissue May 19, `1934, Serial No. '126,617

1': claims. (cl. 2oz-15) y This invention relates to improvements in the gallons of crude oil at 650 F. or 100 gallons oi' coking of heavy oils and residues, such as crude crude cil at 750 F. or 280 gallons of crude oil at petroleums, topped crudes, ilux oils, tars pro- 850 F., approximately may be supplied to the duced' in cracking operations for the production coking operation per 100 gallons of gas oil supoi? gasoline such as pressure still tar, other residplied to the vapor phase cracking operation. The 5 ual oils, and thelike. The invention relates parproduction of a denser coke product is also proticularly to improvements in such coking opermoted by reducing this temperature difference. ations in which the heat for coking is supplied 'Ihe present invention also provides generally by direct heat exchange between the stock to be for the reduction of the temperature difference y l0 coked'and a gaseous uid superheated to a tembetween thetempera'ture prevailing in such cokl0 perature upwards of 900 F., the hot oil products ing operations and the temperature of the stock' discharged from a vapor phase cracking operto be coked as supplied to the coking operation ation, for example. with similar advantages.

In one aspect, this invention is an improve- While, in carrying out the invention, the stock ment in the operations described in my applicato'be coked may befsupplied directly to the iire- 15 tion Serial No. 340,996, filed February 18, 1929; heated preheating heater and then to the coking Patent No, 1,831,719 granted November 10, 1931. operation, this stock is advantageously preheated In other aspects, however, this invention is of by heat exchange with vapors escaping from the more general application. .coking operation before being supplied to the fire- According tp this invention, the oil stock to heated preheating heater. vFor example, this 20 be vcoked is supplied to a coking receptacle within stock o`r part of it'may be used as a cooling mediwhich the coking medium is releasedas a superum in `fractionating operations to which vapors heated gaseous fluid and this stock is thereby refrom the' Icoking operation are subjected or -this u duced to coke, the coking medium is superheated stock orlpart` of it may be used as a scrubbing in a fire-heated heater prior to its introduction Y medium in a scrubbing operatlon'to which vapors 25 into the coking receptacle, and the stock to be fromV the coking operation are subjected. Again coked is preheated in a separate re-heated heatfor example, in applying this invention in coner to a temperature just short of that at which junction with the type of combined operation the deposition of coke' in the fire-heated heater described in Patent No. 1,831,719 mentioned I begins prior to its introduction` into the cokabove, the stock to be coked may advantageously 30 ing receptacle. The stock to be coked isV adbe supplied to the scrubbing operation, and there vantageously so preheated to a temperature uppreheated by direct heat exchange with the vawards of 700 F. or betternpwards `of 800,o F. l pors vfrom the, coking voperation the resulting- In carrying out a' combined vapor phase crackresidual stock mixture then further preheated ing and coking operation as described in' Patent in a fire-heated heater, and this stock mixture 35 No. 1,831,719 mentioned above, for example, then supplied to the coking operation. there is usually a difference o'f as much as 150- The present invention may be applied in con- 300 F. or more between the temperature prevailjunction with cracking operations for the proing in the coking operation andthe temperature duction of gasoline which produce residual tars 40 of the residual stock mixture supplied to ythe with 'special advantage, and the lnventionin- 40 coking operation as discharged Ffrom the scrubcludes certain such combined operations. Residbing operation to which the vapor mixture from ual tars from pressure distillation cracking procthe coking operation is subjected. The present esses, in which a vapor mixture including vapors invention provides particularly for the reduction of the cracked gasoline product are taken oil' of this temperature difference in this type of from a charge of oil undergoing distillation un- 45 operation and ,in this aspect the invention has at der `pressures of say 90-125 pounds per square least two important advantages. 'I'he economy inch, or higher pressures, or residual tar compoof the combined operation is materially pronents of cracking stocks from, high pressure crackrnoted by reducingfths'temperature diilerence; ing processes-ln which separation of the vapors .50 for example, charging heavy reduced crude oil of the cracked gasoline product is effected under to the coking operation and light gas oil-to the pressures lower than those under which the major vapor phase cracking operation and maintaining heating or heating anddigesting is carried out,

a vapor discharge temperature from the coking may be reduced to coke in accordance with thisv operation approximating 900 F. and from -the invention with special advantage. Residual tars cracking operation approximating 1100" F., 50 from low pressure cracking processes may also 55 be reduced to coke `in accordance with` this invention.

In one! particularly advantageous combined operation embodying the invention, the total hot oil products of a high pressure cracking process are discharged with reduction of pressure into a 4combined evaporating and scrubbing receptacle, a scrubbing medium, such as an oil stock to be coked or a refluxing medium condensing from the components vaporized in this receptacle a ceptacle is thus made tolserve a number of functions in a particularly advantageous manner; these functions including separation of lower boiling components from tar components of the cracked stock, direct incorporation of these tar components in the stock mixture to be coked, scrubbing of the vapors from the coking operation and initial pre-heating, preceding the reheating, of the st'ock mixture to be coked. Such composite hot oil products of a high pressure cracking operation may also be discharged, as the pressure is reduced, directly into the receptacle in which the coking operation is carried out.

In another particularly advantageous combined operation embodying the invention, the residual tar from a pressure distillation cracking process is discharged with reduction of pressure into a combined evaporating and scrubbing receptacle,`

a scrubbing medium, such as a stock to be coked or a refluxing medium condensing from the components vaporized in this receptacle a stock to be coked, is supplied to this combined evaporating and scrubbing receptacle, the resulting residual stock mixture from the combined evaporating and scrubbing receptacle including the residual components of the tar from the pressure distillation operation is reheated in a fire-heated heater and then supplied to the coking operation, and the vapors from the coking operation are introduced into the evaporating and scrubbing receptacle. The combined operation of the evaporating and scrubbing receptacle is thus made to serve a number of functions in a particularly advantageous'manner; these functions including separation of vaporizable oil components from the cracked tar, directincorporation of the remaining tar in the stock mixture to be coked, scrubbing of the vapors from the coking operation and initial preheating, preceding the reheating, of

the stock mixture to be coked. Such residual tars may also be discharged, as the pressure is reduced, directly into the receptacle in which the coking operation is carried out. The residual stock remaining after an inital separation of vaporizable oil components from such residual tars, by'reduction of pressure in a preceding evaporating operation, for example, may also be discharged into such a combined evaporating and scrubbing receptacle or into the receptacle in which the'coking operation is carried out.

In another particularly advantageous combined operation embodying the invention, crude oil, the residual components of which are to be coked,

is heated to a distillation temperature in a reheated heater, as in conventional pipe-still practice, for example, and then introduced either into the receptacle in which the coking operation is carried out or into a combined evaporating Aand scrubbing receptacle from which a residual stock mixture is supplied to the receptacle in which the coking operation is carried out. This operation is Y also applicable to reduced or topped crude oils. In some aspects, this operation is applicable for the production of distilled lubricating oils from such crude stocks. In another such combined operation embodying the invention, crude oil, the residual components of which are to be coked, is heated to a distillation temperature in a i'lreheated heater, as in conventional pipe-still practice, for example, and then introduced into an evaporating receptacle, a combined evaporating and scrubbing receptacle into which the vapors from the coking operation are introduced, for example, and the residual stock from this evaporating receptacle is reheated in a separate re-heated heater to a temperatureupwards of `700" F. or better upwards of 800 F. and then introduced either into the receptacle in which the coking operation is carried out or into a scrubbing receptacle, the combined evaporating and scrubbing receptacle mentioned above, for example, from which a residual stock mixture is supplied to the receptacle in which the coking operation is carried out. This operation has a number of special advantages, particularly in that a residual stock free from lower boiling components may thus be supplied to the fire-heated heater through which the stock last passes on its way to the cok-- ing operation proper, as mentioned below.

The invention will be further described in connection with the accompanying drawing which illustrates, diagrammatically and conventionally in elevation with parts in section, one form of apparatus adapted for carrying out the invention. It will be understood that other and different apparatus may be used. It will also be understood that the accompanying drawing is intended, primarily, to illustrate the relation of operations in processes embodying the invention; for example, in practice coking receptacles such as the four illustrated are usually arranged as a compact' group making the connections4 between them much shorter than these connections appear in the drawing and the. several heaters illustrated are, in practice, usually arranged close to the coking receptacles or scrubbing receptacle to Which they are connected. It will also be underelement with the heaters E, F and G respectively) arranged in a heating flue 2, a fan 3 for circulating the heating gases from the fire-box il through Y the heating ilue 2, and ducts 5, 6, 'l and 8 provided With dampers (as shown) for recirculating part of the heating gases through the heating flue 2 and for discharging part of the heating gases to a stack (not shown) through an air preheater (not shown) for supplying preheated air for combustion through duct 9 to the lire-box C.

` for example.

`heater E, with a connection I3 for supplying oil stock supplied through connection 90 or the preheated oil stock discharged from heater G to the receptacle, with a connection I4 for releasing within the `receptacle hot oil products discharged from heater F, and with a connection I6 for conveying the vapor mixture from the receptacle to the scrubbing tower I0. Valves I1, I3 and I9 and valves 23, 24 and 26 are provided to permit, for example, the discharge of the hot gaseous fluid discharged from heater E through connection 21 and the discharge `of hot oil products discharged from heater G through connection 28, respectively, into the'coking receptacles A, B, C, D, A, etc., in succession and valves 29, 33 and 34 are provided to permit, for example, the discharge of the vapor mixture from the coking receptacles A, B, C, D, A, etc. in succession into the scrubbing tower I through connection. Valves I1, I8, 23, 24, 29

and 33 are shown as positioned while carrying out a coking operation in receptacle A, rceptacle B then being charged for the next coking operation, receptacle C then being steamed out and receptacle D being cleaned after discharge of the coke product of the preceding coking operation, as described in Patent No. 1,873,024, mentioned above.

i. Valves I1, I8,-I9, 23, 24, 2S, 29, 33 and 34 may,

" of the tower.

with advantage, be of the type described in Patent No. 1,857,279, granted May 10, 1932, on an application of Eugene C. Herthel and Willis S. Gullette.

The connection I2 may be arranged to discharge into the lower part of the coking receptacles or as describedin Patent No. 1,873,068, granted August 23, 1932, on an application of George H. Taber, Jr., and Edward W. Isom. The connections I3 and I4 maygbe arranged to discharge into the n adapted for maintaining a liquid body of oil during operation normally submerg'lng the inlet con- Y nection 31 througliwhich connection 36, from the interme- Vdiate part is provided with open ballles 38 and the coking receptacles, discharges. The

upper part is provided with bubble plates 3S. Connections 4I and 42 are provided for the introduction of a reiluxing medium into the upper part Reflux condenser Il is also provided for supplying a reuxing medium to the upper part of the tower. Vapors escape lfrom the upper part of `tower I0 through connection 43 either to the lower part of tower 2B through connection 44 or to the lower part of tower30 through connections 45 and 46 or to tower 40 through connections 45, 41 and 48. v

' The fractonating towers illustrated, 20 and 30, may be of conventional bubble tower construction. Either or both ofthese towers may be operated as described in Patent No. 1,810,048y mentioned above. Connections 49 and 5I are provided for supplying raw oil stock to the lower part of these towers. Raw oil stock, raw gas oil for example, may be supplied to tower 30 or in part to tower 30 through connection 5I or totowr 20 or in part to tower through connection 49 or 4to tower I0 or in part to tower I0 through connection 4I, through connection 52 by means of pump 8E. The-operation of the towers 20 and may be controlled by means of either or both of the reflux condensers 2| and 22 or either or both of the reux condensers 3| and 32, respectively. An extraneous cooling medium, water, for example, may be circulated through the heat exchanging cols inv either or both by the reilux condensers 22 and 32.

The refining tower 40, in conjunction with the fractionating tower 50,`may, with advantage, be arranged and operated as described in application Serial No. 257,958, filed February 29, 1928, by Eugene C. Herthel, granted November 11, 1930, as Patent No. 1,781,388. The rening tower is arranged to subject a vapor mixture passing therethrough to the action of an adsorptive catalystl high boiling components produced by the vapor- 9 catalyst contact, and any other constituents higher boiling than suitabley as components of the desired product. The operation of the fractionating tower 50 may be controlled by the regulated introduction of a refluxing medium through connection 54 by means of pump 56; a part of the product supplied through connection 51 or some similar oil fraction supplied through connection 58, for example. The higher boiling components separated in the tower 50 may be introduced, in whole or in part, into the tower I0 through connections B2 and 42 or discharged through connections 62 and 63 by means of pump 55. The vapors forming the product, gasoline, for example, escape from the upper part of tower 50 through connection 59 to condenser 60 which condenser discharges into receiver 10 from which receiver the product is discharged through connection 1I and uncondensed vapors and gases through conr nection 12.

Instead of being discharged through the relning tower 40, the vapor mixture escaping through connection 48 may, for example, be discharged through connection 6I to a condenser similar to condenser 60 connected to a receiver similar to receiver y1I).

When the tower 20 is in operation, the conl densate separated therein is either discharged -through connections 64 and 65er supplied to heater G through connections 64, 66 and 61 by means of hot-oil pump 25. When the tower 30' is in operation, `the condensate separated therein ls either discharged through connections 68 and G9 or supplied to heaterE through connections 68, 13 and 14. Other stocks (water or steam in the case of heater E, for example) or additional stocks may be supplied to the heater E through connections 15 and 14 or to the heater G through* connections 16 and 61. Raw stocks or residual oil stocks may be supplied through connection 11 byl means of pump 89, passed in whole or in part through the heat exchanging coils in the reflux condenser 3|, passed in whole or in part through the heat exchanging coils inthe reilux condenser 2l, passed in Whole'lor in part through the heat exchanging coils in the-,redux condenser II, and then introduced into the lower part of tower I II through connections 18 and 13 or in part introduced into the lower part of tower III and in part supplied to the heater F through connections 18, 88 and 84. Residual oil stocks, tars' from oil cracking operations, for example, may be supplied to the lower part of tower Il) through connection 8|, or the to'tal hot oil products from a high pressure cracking operation, for example, may be supplied to the lower part of tower Il) through connection 8|, or the hot oil products discharged from heater G may be .supplied to the lower part of tower I through connections 28 and 82. The residual ystock mixture formed in the tower I0 is supplied to the heater F through connections 83 and 84 by means of hot oil pump I; part of this stock mixture may be by-passed through connection 85 tothe manifold 81 connecting the heater E, discharge connection 88 and the connections I4 to the coking receptaclesv A, B, C and D.

vThe particular type of hot oil pump illustrated,

designated I5, 25, 35 and 55 is described in more detail in Letters Patent No. 1,701,198 issued February 5, 1929, to'zthe Sinclair Refining. Company on the application of Thomas de Colon Tiit.

This invention will be further illustrated by the following examples of processes embodying the invention as carried out in the apparatus illustrated in the accompanying drawing.

First cxample.-Water is supplied under pressure to the-heater E through connection and in the heater is converted into superheated steam discharged through connection 21 at a temperature approximating 1200 F. and under a pressure approximating 300 pounds per square inch, for example. Calorized tubes are used with advantage in the heater E for carrying out this operation. This superheated steam, the coking medium, is then discharged into the lower end of coking receptacle A through connection I2a, or into the lower end of one of the other coking receptacles of the group. The stock to be coked is withdrawn from a liquid body maintained in the lower end of tower I8 and forced, bymeans of pump I5, through the heater F and then discharged into the upper end of coking receptacle A through connection I4a, or into the upper end of one of the other coking receptacles of the group. The liquid body of stock in the lower end of tower I0 is maintained at a temperature approximating G50-750 F. and this stock -is discharged from the heater F. at a temperature approximating 825-875 F., for example. 'I'he Vapor mixture from the coking receptacle is discharged into and beneath the surface of the liquid body maintained in the lower end of tower Ill through connections 36 and 31. The raw oil stock to be ccked, a crude oil or a topped crude oil, is supplied to the liquid body maintained in the lower end of tower III through connections 11 and 19 or through heater Gjand connection 82. Topped crudes are usually supplied through connections I -11 and 19 although they may be supplied, or in part supplied, through heater G and connection 82. Raw crudes may be supplied through connections 11 and 19, but such stocks are with advantage supplied through the heater G and there heated to a temperature suilicient to eiect sep" aration, by Vaporization, in the tower I0 of thebulk of components tending to Vaporlze under the conditions prevailing in the heater F. Any tendency towa'rd the deposition of coke in the heater F is reduced by raising the mean boiling point of the stock or stock mixturesupplied to this heater. The towers I0, andv30 are operated, for examyple, as previously described. Condensate separated in tower 20, for example, may be supplied to heater G with the raw stock to be coked or such condensate may be supplied to heater G and the raw stock to be coked supplied directlyto the liquid body maintained inn the lower end of tower.

Ill. Vapors escaping from the upper part of tower IU may also be supplied directly to thelower part of tower without being passed through tower 20. Water separated from the nal condensate is returned to the heater E together with any make-up water required.

Crude stocks or similar stocks containing a lubricating oil fraction may be run in accordance with the foregoing example for the separation of the lubricating oil fraction. The lubricating oil fraction is separated as a condensate in tower 20 and discharged through connections 64 and 65.

Second eample.-Instead `of supplying water to the heater E, as in the foregoing example, a hydrocarbon gas mixture, the gases escaping uncondensed from the receiver 10, for example, is supplied to the heater E through connection 15 and there superheatedto a temperature upwards of 1150 F.' The use of steam as a coking medium, however, is in general more advantageous since it can be heated to a higher temrature without decomposition and since the expense of maintaining circulation of the steam coking medium is usually less than that of maintaining circulation of the gas coking medium.

Third example-Instead of supplying water tcthe heater E, as in the iirst'example, a light gasoil stock is supplied to the heater E through connection 14 and there subjected to a vapor,

phase cracking operation from which the hot oil products are discharged'at a temperature approximating 1120 F. This light gas oil stock may comprse reux condensate or a reux condensate mixture from the tower 30 or a raw stock supplied through connection 15 or a mixture of the two. l

Fourth emanuela-A gas oil stock is supplied under pressure to the heater E through connection 14 and there subjected to a vaporphase cracking opera-tion from which the hot oil products are discharged at a temperature approximating 1100-1150 F. and under a pressure approximating 25 pounds per square inch, for example. 'Ihis vapor mixture, the coking medium, is then discharged into the lower end of cokingv receptacle A through connection I2a, or into the lower end of one of the other coking receptacles of the group. 'Ihis gas oil stock may comprise reux condensate from tower 3l), or a mixture of reflux condensate from tower 30 and raw stock supplied through connection 5I; or raw stockl supplied through connection 15, or a mixture of .raw stock supplied through connection 15 and condensate or a condensate mixture from tower 38. Residual tar from a pressure distillation cracking process, carried out as described in Letters Patent No. 1,598,136, issued August 31, 1926,

to the Sinclair Refining Company on the application of Eugene C. Herthel, for example, is discharged, the ypressure being reduced to a pressure approximating 25 pounds per square inch, for example, into the upper end of coking receptacle A through connections 90 and -I3a, or into the upper end of one of the other coking receptacles of the group. The vapor mixture from the coking receptacle is discharged into and beneath the surface of a liquid body maintained in the lower end of tower I through connections 3s and 31. This 1iquid body of stock 1n the lower scribed. Condensate separated in tower 20 may be supplied to the heater G and the resulting Vhot oil products discharged into the coking receptacle with the stock supplied through connection 90, or condensate separated in tower 2|) may be discharged through connections B4 and 65, or the vapors escaping from the upper part of tower .ID may be supplied directly to the lower part of tower 30 without being passed through tower 20.

Crude stocks to be coked may also be supplied to the liquid body maintained in the lower end of tower III throughV connections \11 and 19 or through heater G and connection 82 in the process of the foregoing example.

Fifth examina- Instead of using the hot oil products discharged from a vapor phase cracking operation as the coking medium, as in the foregoing example, steam or a hydrocarbon gas mixture may be used as the coking medium, as in the first and second examples.

Sixth cumpla-A gas oil stock is supplied under pressure to the heater E through connection 14 and there subjected to a vapor phase cracking operation from which the hot oil products are discharged at a temperature approximating 1l001150 F. and under/apressure approximating 25 pounds per square inch for example. This vapor mixture, the coking medium, is then discharged into the lower end of coking receptacle A through connection Ila, or into the lower end of one of the other coking receptacles of the group. This gas oil stock may comprise reilux condensate from tower 30, or a mixture of reflux condensate from tower 30 and raw stock supplied through connection 5I, or raw stock supplied through connection 15, or a mixture of raw stock supplied. through connection and condensate or a condensate mixture from tower 30. Residual tar from a pressure distillation cracking process, carried out as described in Letters Patent No. 1,598,136, mentioned above, forexample, is released through connection I8l into the lower end of tower II) in which tower a pressure approximating 25 pounds per square inch,'for example, is maintained. The vapor mixture from the coking receptacle is discharged into and beneath the surface of a liquid body maintained in the lower end of tower II! through connections 36 and 31. 'Ihis liquid body includes residual components of the tar released through- F and then discharged into the upper end. ot 701 coking receptacle A through connection Ila, or

into the upper end of one of the otherfcoking receptacles of the group, at a temperature approximating 825-850 F., for example. The towers Ill, and 30 Aare operated, for example, as previously described. Condensateseparated in tower '20 may be supplied to the heater d and. the resulting hot oil products discharged into the coking receptacle, or condensate' separated in tower 2Il may be discharged throughconnections 64 and 65, or the vapors escaping from the upperl part of tower ID may be supplied directly to the lower part of tower 30 without being passed through tower 20.

Crude stocks to be coked may also be supplied to the liquid body maintained in the lower end of tower IIJ through connections 11 and 19 or through heater G and connection 82 in the process of the foregoing example.V

Seventh exampZe.'-Instead of using the hot oil products discharged from a vapor phase` cracking operation as the coking medium, as in the foregoing example, steam `or a hydrocarbon gas' mixture may be used as the coking medium, as in the I lrst and second examples.

Eighth example-A gas oil stock is supplied under pressure to the heater E through connection 14 and there subjected to a vapor phase cracking operation from which the hot oil products are discharged at a temperature approximating 1100-1150 F. and under a pressure approximating pounds per square inch. This vapor mixture, the coking medium, is then discharged into the lower end of coking receptacle A through connection I2a, or into the lower end of one of the other coking receptacles of the group. IIhis gas oil stock may comprise reiiux condensate from tower 3II,` or a mixture of re- Vflux condensate from tower 3D and raw stock supplied through connection 5I; or raw stock supplied through connection 15, or a mixture of raw stock supplied through connection 15 and condensate or a condensate mixture from tower 30. Residual tar from a high pressure cracking process, remaining after vaporization of lower. boiling components following initial reduction of pressure on the total hot oil products ofthe cracking process, the residual tar discharged from the evaporator or expansion chamt ber in the high pressure cracking process described in Letters Patent No. 1,675,558, issued July 3, 1928, tovthe Sinclair Refining Company, on theA application of Edward W. Isom andy Charles L. .Parmelee, for example, is supplied to a liquid body maintained in the lower end of tower I0 through connection 8I.. vThis liquid body of stock in the lower end of tower i0 is maintained at a temperature approximating '1D0-750 F., forl example. Stock is withdrawn from `this liquid body and forced, by means of pump I5, through the heater F and then discharged into the upper end of coking receptacle A through connection Illa; or into the upper end of one of the otherV coking receptaclesmof the group, at a temperature approximating 850-` 875 for example. The towers I0, 20 and 30. are operated, for example, aspreviously described. Condensate separated in tower 2D may be supplied to the heater G and the resulting, hot oil products discharged into the coking receptacle, or condensate separated in tower 2li may be discharged through connections M and 65 or the vapors escaping from the upper part of tower IIJ'may be supplied directly, to the lower part of tower 30 without being passed through tower 2li.

through heatenG and connection 82 in-the proces's of the foregoing example.

Ninth. example-Instead of using the hot oil products discharged from a vapor phase cracking operation as the coking medium. as in the foregoing example, steam or a hydrocarbon gas mix- I ture may be used as the coking medium, as in the first and second examples.

y Tenth mamma-Instead' of supplying residual tar from a high pressure cracking process to the liquid body maintained in the lower end of tower I0, as in the eighth and ninth examples, the total hot oilproducts of a high pressure cracking process are released, the pressure being reduced to a pressure approximating pounds per square inch, for example, within the lower end of tower I0 through connection 8|. For example, a gas oil stock is supplied under pressure to the heater ,G through connection 16 and there subjected to a high pressure cracking operation from which the hot oil products are discharged at a temperature approximating 850-950" F. and under a pressure approximating 40G-600 pounds per square inch, for example, and the total hot y Oil products of this operation are released, with reduction of pressure as discharged from the heater G, into the lower end of tower I0 through connections 2B and 82. v

Eleventh example-Instead of releasing the total hot oil products of a high pressure cracking operation into the lower end of tower l0, as in the tenth example, the total hot oil products of a high pressure cracking operation aresdischarged with reduction of pressure, into the upper end of coking receptacle A through connections and I3a, or into the upper end of one of the other coking receptacles of the group.

It will be understood that the foregoing examples are for the purpose of exempliiication and that the invention is not limited to the opi erations there described as carried out in the apparatus illustrated in the accompanying drawing.

The present invention provides,` in its more advantageous embodiments, a combined operation in which the advantages of a relatively low temperature difference between the temperature prevailing in the coking operation and the temperature of the stock to be coked as supplied to the coking operation. as previously mentioned, are .securedV and further in which particularly favorable conditions are maintained with respect to operation o! the lire-heated heater in which the stock to be coked is preheated. Inthese more advantageous embodiments of the invention, the stock supplied to this fire-heated heater contains a minimum of components tending to vaporize in the heater. Such components are separated, for example, in the scrubbing operation. In this respect, the invention makes possible the maintenance of ,a higher discharge temperature from this heater, without involving difiiculties due to deposition of coke therein, and consequently makes possible the maintenance of a lower tempera.- ture difference between the temperature prevailing in the coking operation and the temperature oi! the stock to be coked as supplied to the coking operation.'

I claim:

1. In coking hydrocarbon oils, the improvement which comprises supplying a hydrocarbon oil to a vapor phase cracking operation, vaporizing and V cracking the oil in the vapor phase therein, re-

leasingthe hot vapor mixture from the vapor phase cracking loperation at a temperature upwards of 900 F. within a coking receptacle, separatcly preheating a heavy hydrocarbon oil to be coked by the addition of heat from an extraneous source and simultaneouslyintroducing said heavy hydrocarbon oil to be coked into the coking receptacle at a rate at least as great as that at which oil is supplied to the vapor phase cracking operation and at a temperature less than F. lower than the temperature prevailing in the coking receptacle, and reducing the heavy oil to coke therein.

2. In coking hydrocarbon oils, the improvement which comprises supplying a hydrocarbon oil to a vapor phase cracking operation, Vaporizing and cracking the oil in the vapor phase therein, releasing the hot vapor mixture from the vapor phase cracking operation at a temperature upwards of 900 F. within `a coking receptacle, heating a heavy hydrocarbon oil to be coked to a temperature upwards of about '750 F. by supplying heat thereto from an extraneous source in a heating zone separate from the heating zone used in the vapor phase cracking operation, introducing the thus preheated heavy oil into the coking receptacle into direct contact with the hot vapor mixture discharged from thevapor phase cracking operationJ at a rate at least as great as that ,at-Which oil is supplied to the vapor phase cracking operation, and reducing said heavy oil to coke therein.

3. In coking heavy hydrocarbon oils,.'the improvement which comprises heating a iluld coking medium to a temperature upwards of 900 F. in a heating zone by supplying heat from an extraneous source and releasing the thus heated coking medium within a coking receptacle, heating a heavy oil stock to be coked to altemper'ature upwards of about '750 .F. in a separate heating zone by supplying heat from an extraneous source and introducing the thus preheated stock into the coking receptacle at a rate at least as great as that at which the iiud coking medium is supplied to the said heating zone, and reducing the said heavy oil stock to coke in the coking receptacle.

4. In coking heavy hydrocarbon oils, the improvement which comprises heating a fluid coking medium to a temperature upwards of 900 F. in a heating zone by supplying heat-from an extraneous sourceand releasing the thus heated coking medium within a coking receptacle, heating a heavy oil stock to be coked to a temperature upwards of 800 F. in a separate heating zone by supplying heat from an extraneous source and introducing the thus preheated stock into the coking receptacle at a rate at least as great as that at which the fluid coking medium is supplied to the said heating zone, and thereby reducing the said heavy oil stock to coke in the coking receptacle.

5. In coking -hydrocarbon oils, the improvement which comprises heating a hydrocarbon oil in a heating zone to vaporize the oil and crack the vapors in the vapor phase, releasing the hot vapor mixture from the vapor phase cracking operation at a temperature upwards of 900 F. within y a coking receptacle, discharging the hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body of heavy hydrocarbon Yoil in a scrubbing receptacle, withdrawing liquid 'cil from said body and heating the oil so withdrawn to a temperature upwards of '700 F. by supplying heat thereto from an extraneous source in a heatingzone separate from the heating zone used in the vapor phase crack- 75 oil into the coking receptacle and reducing it to coke therein. y

6. In coking hydrocarbon oils., the improvement which comprises heating a hydrocarbon oil in a heating zone to vaporize the oil and crackthe vapors in the vapor phase releasing the hot vapor mixture from the vapor phase cracking operation at a temperature upwards of 900 F. within a coking receptacle, supplying heavy oil stock to be coked to said coking receptacle, discharging the hot vapor mixture from the coking receptacle vinto and beneath the surface of a liquid body of' a heating zone to vaporize the oil and crack it in the vapor phase, releasing the hot vapor mixture fromthe vapor phase cracking operation at a temperature upwards of 900 F. within a coking receptacle, discharging the hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body of heavy hydrocarbon oil in a scrubbing receptacle, supplying heavy oil stock to be coked tosaid scrubbing receptacle, withdrawing oil from said liquid body and heating the oil so withdrawn to a temperature upwards of '700 F. by supplying heat thereto from an extraneous s ource in a heating zone separate from the heating zone used in the vapor phase cracking operation, and introducing the thus heated oil into the coking receptacle and reducing it to coke therein.

8.-,In coking tars from cracking operations in Which'hydrocarbon oils are cracked -for the production of gasoline and the low boiling products\ are separated from the tar 'by distillation, the improvement which comprisesheating a hydrocarbon oil in a separate heating zone to vaporize the oil and crack the vapors in'the Vapor phase, releasing the hot vapor mixture from a vapor phase cracking operation at a temperature upwards of 900 F. within a coking receptacle. simultaneously supplying'tar from a cracking operation of the type first mentioned to said coking receptacle, Ldischarging the hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body of heavy hydrocarbon oil in a, scrubbing receptacle, withdrawing oil from said liquid body and heating the oil so withdrawn to a temperature upwards of 700 F. by supplying heat thereto from an extraneous source in a heating zone separate from the heating'zone used in the vapor phase cracking operation, introducing v in the coking receptacle.

the thus heated oil into the coking receptacle in direct contact with the hot vapor mixture from the vapor phase cracking operation, and thereby reducing the thus heated oil and the tar to coke 9. In coking tars from cracking/'operations in which hydrocarbon oils are cracked for the production of gasoline and the low boiling products are separated from the tar by distillation, the improvement which comprises heating a hydrocarbon oil in a separate heating zone to vaporize the oil and crack the vapors in the vapor phase,l

releasing the hot vapor mixture from the vapor phase cracking operation at a temperature upwards of 900 F. within a coking receptacle, discharging the hot vapor mixture from the coking receptacle into and beneath the surface of a -liquid body of heavy hydrocarbon oil in a scrubheat thereto'from an extraneous source in a heating zone separate from the heating zone used in the vapor phase cracking operation, and introducing the thus heated oil into the coking receptacle vinto direct contact with the hot vapor mixture discharged from the vapor phase cracking operation and reducing it to coke therein.

10. In coking tars from cracking operations for the production of gasoline, the improvement .which comprises heating a fluid coking medium to a temperature upwards of 900 F. by supplying heat thereto from an extraneous source in a heating zone and releasing the thus superheated coking medium within a coking receptacle, heating a tar from a cracking operation for the production of gasoline to a temperature upwards of about '750 F. in a separate heating zone by supplying heat thereto from an extraneous source and introducing the thus preheated tarv into the coking `ture from the vapor phase cracking operation at a temperature upwards of 900 F. within a coking receptacle. discharging the hot vapor mixture from the coking receptacle into a scrubbing receptacle, cracking ka heavy hydrocarbon oil under high pressure and discharging the total hot oil products of the high pressure cracking operation with reduction of pressure into the scrubbing receptacle, separately supplying a liquid hydrocarb`on oil to the scrubbing receptacle, scrubbing the vaporsv with said liquid hydrocarbon oil in the scrubbing receptacle and dischargingvapors therefrom, withdrawing a residual 'oil mixture from the scrubbing receptacle andvheating the residual oil mixture withdrawn from the scrubbing receptacle to a temperature'upwards of '700 FL by supplying heat thereto from an extraneous source in a heating zone separate from the heating zone used in the vapor phase cracking operation, and introducing the thus heated oil mixture into the coking receptacle into direct contact with the hot vapor mixture discharged from the vapor phase cracking operation and reducing it to coke therein.

' 12. In coking tars from cracking operations in which heavy hydrocarbon oils are cracked under Areceptacle at a rate at least as Agreat as that at 4 high pressure for the production ofgasoline and the low boiling products are separated from the tar by distillation, the improvement which comprises heating a hydrocarbon oil in a heating zone to vaporize the oil and crack 4it in the vapor charging residualqtar from a separate cracking operation of the type rst mentioned with reduction of pressure into the scrubbing receptacle, supply-ing a liquid oil as a scrubbing medium to the scrubbing receptacle, scrubbing the vapors with said liquid oil in the scrubbing receptacle and` discharging vapors therefrom, withdrawing l a residual oil mixture from the scrubbing receptacle and heating the residual oil mixture `withdrawn from the scrubbing receptacle to a temperature upwards of 700 F. by supp-lying heat thereto from an extraneous source in a heating Zone separate from the heating zone used in the vapor phase cracking operation, and introducing the thus heated residual cil mixture into the coking receptacle into direct contact with the upwards of 900 F., supplying heat thereto from` an extraneous source in a heating zone separate from the first mentioned heating\zone and releasing the thus heated coking medium within the coking receptacle, discharging Athe hot vapor mixture from the coking receptacle into a scrubbing receptacle, discharging vapors from the scrubbing receptacle, withdrawing a residual oil mixture from the scrubbing receptacle and heating the residual oil mixture withdrawn from the scrubbing receptacle to a temperature upwards of '700 F. by supplying heat thereto from an extraneous source in a heating zone separate from the first two mentioned heating zones, and introducing the thus heated residual oil mixture into the coking receptacle into direct contact with the fluid coking medium discharged from the second said heating zone and reducing the residual oil mixture and the crude oil stock to coke therein.

14. In coking crude oil stocks, the improvement which comprises heating a crude hydrocarbon oil stock to a distillation temperature in a heating zone by supplying heat thereto from an extraneous source and introducing the thus heated stock into a scrubbing receptacle, heating a iluidzcoking medium to a temperature upwards of 900 F. in a separate heating zone by supplying heat thereto from an extraneous source and releasing the thus heated cokingv medium within a. coking receptacle, discharging the hot vapor mixture from the coking receptacle intothe scrubbing receptacle, discharging vapors from the scrubbing receptacle, withdrawing a residual oil mixture from the scrubbing receptacle and heating the residual oil mixture withdrawn from the scrubbing ireceptacle to a temperature upwards of 700 F. in another heating zone-sepa rate from the first two mentioned heating zones by supplying heat thereto from an extraneous source, and introducing the thus heated residual oil mixture into the coking receptacle into direct contact with the fluid coking medium released from the second mentioned separate heating zone and reducing it to coke therein.

15. In coking crude oil stocks, the improvement which comprises heating a uid coking medium to a temperature upwards of 900V F. in a heating zone by supplying heat thereto from an extraneous source and releasing the thus heated coking medium within a coking receptacle, discharging the hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body` of heavy hydrocarbon oil in a scrubbing receptacle, supplying a crude h yf drocarbo-n oil stock-to said liquid body of oil, withdrawing liquid oil from said body and heating the oil withdrawn from said liquid body to a. temperature upwards of 700 F. by supplying heat thereto from an extraneous source in a separate heating zone, and introducing the thus heated oil into the coking receptacle into direct contact with the fluid coking medium released within the coking receptacle and reducing it to n0 coke therein.

16. In coking hydrocarbon oils, the improve- `ment which comprises releasing superheated steam at a temperature upwards of 900 F. within a' coking receptacle, discharging a hot vapor mixture from the coking receptacle into and beneath the surface of a liquid body of heavy hydrocarbon oil in a scrubbing receptacle, withdrawing liquid oil from said body and heating oil withdrawn from said liquid body toa temperature upwards of '700 F. by supplying heat there- ,40

to from an extraneous source in a separate heatving zone, and introducing the thus heated oil into the coking receptacle and reducing it to coke therein.

17. In coking hydrocarbon oils, the improvement which comprises heating a heavy hydrocarbon oil to be coked to a temperature upwards of about 750 F; in a heating zone bysupplying heat thereto from an extraneous source and introducing the thus preheated oil into a coking receptacle, and heating steam to a temperature upwards of 900 F. by supplying heat thereto from an extraneous source in a separate heating zone, and releasing the thus superheated steam within the coking receptacle at a rate' not exceeding the rate at which said stock to be coked is supplied to the coking receptacle, and reducing said stock to coke inthe coking receptacle.

HARRY L. PELZER. 

